1. Field of the Invention
This invention relates to a method of forming isolation zones for light transmission in a compound semiconductor optical integrated circuit.
2. Description of the Prior Art
It is theoretically known that when a light is transmitted between two substances having different refractive indexes, the light is focused in one substance having a refractive index higher than that of another substance and propagated in a longitudinal direction by repeated total reflections at a boundary face between both the substances. Therefore, various attempts have been made in order to obtain light transmission paths in a compound semiconductor substrate; for instance, transparent band-shaped bodies having a higher or lower refractive index are formed in a transparent substrate having a certain refractive index, whereby the substance having the more higher refractive index is used as the light transmission path. However, a satisfactory result is not yet obtained.